export default (function (o, c) {
  var proto = c.prototype

  proto.isoWeeksInYear = function () {
    var isLeapYear = this.isLeapYear()
    var last = this.endOf('y')
    var day = last.day()

    if (day === 4 || (isLeapYear && day === 5)) {
      return 53
    }

    return 52
  }
})
